From Sky and Telescope, Bob King wrote"
With a subtle beauty all its own, the earthshine we see glowing
in the lunar night invites us to consider Earth's many connections to the Moon.
Often referred to as the "ashen
light" or "the old Moon in the New Moon's arms," earthshine begins it lunar journey literally at your doorstep.
Sunlight reflected from our planet radiates into space. A portion of it passes the Moon, strikes
the lunar surface, and reflects back to our eyes. Much of that light is absorbed by the charcoal-dark lunar soil, which is
why the earthlit Moon appears faint. From the surface of the Moon, ground illumination would resemble deep twilight here on
Earth. By comparison, the bright crescent is illuminated by direct sunlight.
These are great nights to do sidewalk observing and help the public understand the connections between
the Earth and Moon.
Read more about Earthshine and the best nights to observe.